Collet for precious stones

ABSTRACT

A collet system for embedding and clamping precious and non-precious stones on a support to create a jewel where the stone is mounted, characterised in that the collet ( 1, 21, 30 ) is made up of a straight or round polygonal closed contour having various projections ( 2 22, 32 ) towards the outside and the inside alternatively; in that vertical grooves ( 3, 23, 31 ) are made in said projections towards the inside from bottom to top, such grooves not reaching the upper face of the collet ( 1, 21 ) or having a narrow dimension, thus creating a shape or dimensional shoulder towards the tops; in that such grooves ( 3, 23 ) have to precisely hold and clamp a cylindrical pin ( 5, 25, 35 ) having dimensions matching the grooves ( 3, 23, 21 ) to clamp the stone ( 8, 28, 38 ).

This invention refers to the mounting of precious stones, semi-precious stones and the like to produce jewels and ornaments obtaining a mounting which complements and sets off the stone.

In the prior art there is a great variety of techniques for fixing and clamping precious stones, generally considered as coupling, support and clamping systems of the stone inside the jewel. Generally, precious and semi-precious stones, in jewellery and costume jewellery, can have very different cuts and shapes and the technique to fix and couple them to the jewel's underlying frame requires a particular adjustment according to these shapes and to the conformation of the seat which must receive them. According to the seat which has to receive the stone, two fundamental embedding systems are possible: embedding on a metal sheet, which has embeddings commonly called “pave”, “beating” or beaten track, or the embedding in a collet or in a “bastina” or in a bezel: generally, by collet it is meant a tubular hollow with a perimeter equipped with fixing projections for fixing an essentially round stone, by “bastina” it is meant a universal metal structure varying in shape to embed and fix stones having various shapes and cuts.

Among the systems to embed and fix stones the most widespread are the fixings commonly called pavé, beating, bezel and “baffo”. The pavé technique foresees the perforation and the carving of a metal sheet, causing a partial raising of the cut edge, so as to form portions in relief so as to form raised parts, or “granette”, which are then bent on the edge of the stone clamping it inside the carving. The stone is however partially embedded in the metal sheet to the detriment of its visibility and its light. In the same way, the beating technique foresees the introduction of the stone on two parallel sheets, or a single sheet, or on a collet, which have already been prepared with a slight deformation of their perimeter. The stone is clamped to the base arranged in this way clinching said perimeter with a tool, commonly known as beater, on the girdle of the stone or on its sides. With the beating technique as well, the stone is embedded in the metal support losing light and visibility.

The bezel clamping technique foresees the use of a frame formed from a metal thread over which a sort of spiked crown is mounted, where the stone is inserted bending the spikes pressed on the edges of the stone.

Such a technique does not embed the stone in metal, but it stays inside its bezel or “crown” in any case. A further clamping technique is the one commonly known as “baffo”. A series of curls, or small metal protruding edges, which have to hold the stone, are formed from the lower edge of the clamping collet. Such a technique allows the full size of the stone to be shown with a less heavy embedding, but it does have problems of effectiveness and safety.

On the whole, the technique commonly used involves embedding the stone in a quite heavy and encircling structure which limits its visibility and which harm its light features which make a jewel stone “precious”. The present invention has the purpose of realising a light and reliable stone embedding, so as to hold and clamp the stone, however leaving its edge completely uncovered, allowing the entire surface of the stone to be lighted, enhancing its features and visibility. The invention foresees a collet, that is to say a seat for the stone, with a special shape enabling an embedding with higher visibility. Such embedding is no longer a support, like in the prior art, surrounding the stone to the detriment of its beauty, but is a dot-shaped clamping element with a limited number of points. It is totally reliable and it does not harm the beauty of the stone.

The purpose of the invention is that of realising a support for the stone to be clamped on the jewel, which leaves it almost free from the metal collet, and which allows light to be cast on the whole surface enhancing its features and its shape.

This purpose is attained by making an embedding or support system, for a precious or non-precious stone according to the present invention, defined in its widest meaning of device, in the first claim and for its preferential or alternative embodiments in those claims depending on it. Said embedding system is defined in its widest meaning of embedding procedure, in the twelfth claim and, for the preferential or alternative embodiments in those claims depending on it.

The characteristics and advantages of the collet system according to the present invention shall become clearer from the following description, given as an example and not for limiting purposes, referring to the attached drawings, in which:

FIG. 1 represents a view from above of the collet or stone support;

FIG. 2 is an A-A section view of the collet of FIG. 1 with the pins taken out;

FIG. 3 is an A-A section view of the collet of FIG. 1 with the pins inserted;

FIG. 4 is a view from below of the collet of FIG. 3 with the stone inserted;

FIG. 5 is a view from above of the collet of FIG. 3 with the stone inserted;

FIGS. 6A and 6B show details of the structure and mounting of the collet according to the present invention;

FIG. 7 illustrates alternative shapes of the pins for engaging and clamping the stone;

FIGS. 8, 8A, 8B and 8C show a further variant embodiment of the present invention;

FIG. 9 shows a plan view illustrating another possible embodiment of the present invention.

FIG. 1 shows a view from above of the collet according to the present invention. It is made up of a polygonal straight or round closed contour 1, having a plurality of projections alternatively towards the outside and the inside, for example in the shape of a four-leaf clover, as shown in FIGS. 1 to 7.

Vertical, cylindrical grooves 3 are made from the bottom to the top in the inner projections 2 of the contour of the collet 1, preferably in circular section. As shown in FIGS. 2 and 3, such grooves do not reach the upper side of the collet, but stop before getting to the upper surface 4 of the collet thus making a shoulder towards the top. In the embodiments shown in FIGS. 1 to 7, such vertical cylindrical grooves are open towards the inside with a round clamping section according to an angle greater than 180 degrees and each is intended to accurately hold and clamp a single cylindrical clamping pin 5 whose dimensions are proportionate to the grooves or hollows 3. FIG. 3 shows the pins 5 already placed in their hollows 3. There can be three or more mounting points of the stone 8 but in general their number is limited to between four and six.

According to an alternative embodiment of the present invention, the hollows 3 and the pins 5 have a slightly conical or bell mouthed shape so as to assure a better mutual coupling and a more effective clamping of the stone.

FIG. 4 illustrates the view from below of the stone 8 inside the collet 1 and with the pins 5 inserted to clamp the stone itself against the upper shoulder. FIG. 5 illustrates the view from above of the stone 8 inside the collet 1, with the pins 5 inserted—but not in view—and with the upper shoulder of the verticis 2 of the upper face 4 protruding over the stone in the verticis 2 leaving the remaining circumference completely free.

FIGS. 6A and 6B show, with greater detail, the mounting and clamping of the stone. The body of the collet 1 receives the cylindrical pin 5 in its hollow 3 to fix the stone 8 against its shoulder 10. The pin 5 does not reach the bottom of the hollow 3, but engages against the lower face of the stone 8 pushing its upper face against the shoulder 10. The upper end of the pin 5, just like the lower face of the shoulder 10, is appropriately rounded or splayed to push the stone against the shoulder. Once the pins 5 are mounted, they can be clamped through known means, to keep the stone's collet secure and effective throughout time.

As FIG. 6B shows, the perimeter of the stone 8 is completely free, apart from the points where it holds against the shoulders 10, and can be lighted enhancing its features. The upper surface of the stone 8 sticks out over the upper face 4 of the collet and is fully visible.

As mentioned above, the shape of the groove or hollow 3 and of the pin 5 can be cylindrical, or slightly conical, but not necessarily with a round section: FIG. 7 illustrates alternative shapes of the hollow 3 and of the pins 5 for engaging and clamping the stone, with a view from below.

Pin and hollow with a round section are shown in position A. The hollow 3 always has a containing angle of greater than 180 degrees, to hold the pin 5 inside without preventing it from turning upon itself. Pin and hollow with double cylinder are shown in position B.

The hollow 3 can be like the previous one or, alternatively, be clamped to hold the pin and avoid it turning upon itself. A pin 3 with a round section with a rectangular gib is shown in position C. In this case the relative hollow 3 can be made always round with a containing angle greater than 180 degrees, i.e. like the second case of position B. A pin 3 with a cam section or droplet shape section is shown in position D. It is like the previous one and its hollow 3 can be made according to the two alternatives previously explained. The variations in the section of the pin 5, according to the alternatives shown in FIG. 7, can be limited to just the upper end, acting as a damper of the stone 8 to provide a larger surface to hold it and clamp it in position.

The variations explained show how pins and grooves can be shaped with a cross-section to suit requirements, being however sufficiently similar so as to provide for a coupling which keeps the pin in the correct position inside the groove.

As already stated, the present invention is susceptible to alternative embodiments to those described up to now.

An alternative embodiment of the collet according to the present invention is shown in FIG. 8, from 8 to 8C. The collet, according to the variant described, is shown from the above in FIG. 8. It is still made up of a closed polygonal contour 30 in the shape of a four leaf clover, as shown in previous figures. The grooves 31 are made in internal projections 32 of the collet's contour 1 from bottom to top, with dihedral section having an angle wider than 90 degrees. Such grooves reach the upper side of the collet, but are tapered from bottom to top narrowing before reaching the upper surface of the collet 34, thus making a dimensional shoulder towards the top. Such tapered grooves 31 can be formed inside the contour 30, or can be obtained by applying “appliqués” 31′ on vertical hollows 31, which have already been made as shown in FIGS. 8A-C.

Pins 35 are adapted to the grooves 31, 31′ which must receive them and narrow in their outer part from bottom to top. In their upper inner part pins 35 contain both the upper and the lower part of the grooves 37 encircling the stone 38. Two opposite pins 35 and a stone 38 are shown in FIG. 8A before the stone is embedded in grooves 37. Two opposite pins 35 with the stone 38 already inserted in their grooves 37 are shown in FIG. 8B. In FIG. 8C, pins 35 integral with the stone 38 have been simultaneously inserted in their grooves 31, 31′ up to the tolerated level of their dimensional narrowing compared to the collet 30, constituting an embedding narrowing from bottom to top and clamping the pins 35 joined with the stone 38 to the set level.

The exemplified number of mounting points of the stone 38 is four.

A variant of the description which has been made could consist of the same collet in which grooves are made which foresee, from the faces of the dihedron, once the embedding is complete, a thrust towards the third central side consisting of the stone.

In this case, like in the previous one, moreover, the 5 pins do not necessarily have to foresee a narrowing of their section. It is sufficient to incline the pins with a constant section upwards, which keeps the upper section (from the top) smaller in side. The effect obtained is that of a lateral thrust which ensures the seal of the stone in complete security.

The view from above of FIG. 9 illustrates a mounting with pairs of opposite grooves 31, 31A, in which the grooves of each pair have a different configuration from that of the grooves of the other pair.

From that which has been described above it is clear, according to the case, that it is possible to carry out the invention using pins with a different section, i.e. an inclined constant section, a non-inclined tapered section, an inclined tapered section. In other words, the pins and/or the grooves can have a cross section of any geometrical shape.

The collet system according to the present invention offers substantial advantages compared to the embedding and clamping systems of precious stones proposed by the prior art, for the system as for the embedding. The following are the relevant advantages among them.

The collet system according to the invention allows a stone clamping with quite a number of points to be obtained which is secure and effective throughout time without encircling the stone, leaving its upper part to stick out of the collet and leaving the entire surface practically free for refracting light.

The collet system according to the present invention can adapt to any contour and stone shape, since it works on quite a number of points of the contour. The polygonal collet contour, with perimetric grooves and projections, offers great ability to adapt to possible unevenness and asymmetries of the edge of the stone to embed in the jewel.

The lobe openings of the polygonal section of the collet let light reach the entire stone including its sides, and enhance its beauty. 

1. Collet system for embedding and clamping precious and non-precious stones on a support to create a jewel where the stone is mounted, characterised in that the collet (1,21,30) is made up of a straight or round polygonal closed contour having various projections (2, 22, 32) towards the outside and the inside alternatively; in that vertical grooves (3, 23, 31) are made in said projections towards the inside from bottom to top, such grooves not reaching the upper face of the collet (1, 21) or having a narrow dimension, thus creating a shape or dimensional shoulder towards the top; in that such grooves (3, 23) have to precisely hold and clamp a cylindrical pin (5, 25, 35) having dimensions matching the grooves (3, 23, 31) to clamp the stone (8, 28, 38).
 2. Collet system according to claim 1, characterised in that the vertical grooves (3, 23) are opened towards the inside of the collet (1, 21) with a round clamping section.
 3. Collet system according to claim 1, characterised in that the vertical grooves are cylindrical (3, 23) and the pins (5, 25, 35) are slightly conical and bell-mouthed (31).
 4. Collet according to one of the claims from 1 to 3, characterised in that the vertical grooves (3) are opened towards the inside of the collet (1) according to a pin containing angle greater than 180 degrees and they precisely hold and clamp a single cylindrical clamping pin (5) whose dimensions match the grooves or hollows (3).
 5. Collet system according to claim 1, characterised in that the pins (5, 25), and or the grooves (3, 23) have a double cylinder cross-section.
 6. Collet system according to claim 1, characterised in that the pins (5, 25), and/or grooves (3, 23) have a round cross-section with a rectangular gib.
 7. Collet system according to claim 1, characterised in that the pins (5, 25), and/or grooves (3, 23) have a cross-section in the shape of a cam or droplet.
 8. Collet system according to claim 1, characterised in that the grooves (31) are made in the internal projections (32) of the contour of the collet (30) from bottom to top, reaching the upper side of the collet, but tapering from bottom to top narrowing before they reach the upper side (34) of the collet, thus making a dimensional shoulder towards the top; in that the pins (35) are adapted to the grooves (31, 31′) that have to hold them, and narrow in their outside from bottom to top; and in that in their upper inner part the pins (35) contain both the upper and the lower part of the hollows (37) clamping the stone (38).
 9. Collet system according to claim 8, characterised in that the grooves (31) are made in dihedral section from bottom to top with an angle greater than 90 degrees.
 10. Collet system according to claim 8, characterised in that the tapered grooves (31) are obtained by applying “appliques” (31′) on vertical hollows (31), applied already in projections (32).
 12. Embedding and clamping procedure of precious and non-precious stones on a support to create a jewel where the stone is mounted, characterised in that the stone (8, 28, 38) is embedded inserting it from the bottom in a collet (1, 21, 30) made up of a straight or round polygonal closed contour and of projections (2, 22, 32) towards the outside and the inside alternatively; in said projections towards the inside being made cylindrical vertical grooves (3, 23, 31) from bottom to top, such grooves being incomplete or tapered thus creating a shoulder towards the top; and in that the stone is then clamped through the accurate introduction in each groove (3,23,31) of a cylindrical pin (5, 25, 35) whose dimensions match those of the grooves (3, 23, 31), to clamp the stone (8, 28, 38).
 13. Embedding procedure of stones according to claim 9, characterised in that the cylindrical vertical grooves (3, 23, 31) and the pins (5, 25, 35) are slightly conical or bell-mouthed. 